JP6711641B2 - Lens driving device, imaging device, control method thereof, and control program - Google Patents

Description

The present invention relates to a lens driving device, an imaging device, a control method therefor, and a control program, and more particularly to drive control of a lens driving device.

2. Description of the Related Art In recent years, image pickup apparatuses such as digital cameras have been used in various ways, and various shooting styles suitable for shooting in various shooting scenes have been proposed. Therefore, for example, there is known an image pickup apparatus including an autofocus mechanism with high mobility for following a subject moving at high speed (see Patent Document 1).

Japanese Patent Laid-Open No. 5-66336

By the way, the movement of the subject and the movement of the image pickup apparatus at the time of shooting are various. When taking an image of a subject whose direction changes frequently, the lens driving device is required to have high responsiveness in consideration of the large movement of the image pickup device. That is, in order to improve the responsiveness, it is necessary to reduce the weight of the movable portion such as the autofocus mechanism in the lens driving device.

However, the reduction in weight may reduce the rigidity, and the movable part may vibrate when stopped. As a result, the settling time of the movable part becomes long, and as a result, the responsiveness is impaired.

Therefore, an object of the present invention is to provide a lens driving device, an imaging device, a control method, and a control program with improved responsiveness.

In order to achieve the above object, a lens driving device according to the present invention is a lens driving device that drives a lens in an optical axis direction, and a holding member that holds the lens and is movable in the optical axis direction, A first detection unit that detects a position of the holding member in the optical axis direction as a current position; a second detection unit that is disposed on the holding member and that detects information regarding deformation of the holding member; Control means for controlling the movement of the holding member based on the position and the information on the deformation.

According to the present invention, it is possible to improve responsiveness when driving and controlling a lens.

FIG. 3 is a block diagram showing a configuration of an example of an image pickup apparatus including the lens driving device according to the first embodiment of the present invention. It is a figure for demonstrating the lens drive device shown in FIG. 1, (a) is a front view, (b) is a side view. 3 is a flowchart for explaining an example of AF (autofocus) performed in the camera shown in FIG. 1. It is a figure which shows an example of the functional block at the time of performing AF processing in the control part shown in FIG. It is a figure for demonstrating the deformation|transformation detected in the 2nd detection part shown in FIG. It is a figure for demonstrating the change with time of the target position, the lens holding frame position, and the lens center position in the conventional lens movement control, (a) is a figure which shows the change of a target position, (b) is a lens FIG. 6C is a diagram showing a change in the holding frame position, and FIG. 6C is a diagram showing a change in the lens center position. FIG. 4A is a diagram for explaining changes in a target position, a lens holding frame position, and a lens center position over time due to lens movement control in the camera shown in FIG. 1, and FIG. 7B is a diagram showing a change in the lens holding frame position, and FIG. 9C is a diagram showing a change in the lens center position. FIG. 6 is a diagram for explaining changes in the position of a lens holding frame used in the camera shown in FIG. 1. It is a figure which shows an example of the functional block at the time of performing AF processing in the control part with which the camera which concerns on the 2nd Embodiment of this invention is equipped. FIG. 10A is a diagram for explaining changes in the target position, the lens holding frame position, and the lens center position over time due to the lens movement control described in FIG. 9, and FIG. FIG. 8A is a diagram showing a change in the lens holding frame position, and FIG. 8C is a diagram showing a change in the lens center position. It is a figure which shows an example of the functional block at the time of performing AF processing in the control part with which the camera which concerns on the 3rd Embodiment of this invention is equipped. FIG. 12A is a diagram for explaining changes in the target position, the lens holding frame position, and the lens center position over time due to the lens movement control described in FIG. 11, and FIG. FIG. 8A is a diagram showing a change in the lens holding frame position, and FIG. 8C is a diagram showing a change in the lens center position. It is a figure for demonstrating an example of the lens drive device by the 4th Embodiment of this invention, (a) is a front view, (b) is a side view. It is a figure for demonstrating detection of the contact state of the lens holding frame and the guide part in the lens drive device shown in FIG. 13, (a) is a figure which shows the state in which the lens is not inclined, (b) is It is a figure which shows the state in which the lens was tilted.

An example of the lens driving device according to the embodiment of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing the configuration of an example of an image pickup apparatus including a lens driving device according to the first embodiment of the present invention.

The illustrated image pickup apparatus is, for example, a digital camera (hereinafter, simply referred to as a camera), and the camera 100 has a camera body 101 and a lens barrel body 105. The camera body 101 is provided with an image pickup unit 102, and an optical image is formed on the image pickup unit 102 via the lens barrel 105. Then, the image capturing unit 102 generates image data according to the optical image.

The image pickup unit 102 includes an image pickup device having a plurality of pixels, and the focus detection unit 123 sets the distance to the subject as the subject distance based on the parallax according to the image pickup result (image data) obtained by the image pickup device. Detect (that is, perform focus detection). Then, the control unit 124 drives and controls the lens driving unit 110 based on the subject distance obtained by the focus detection unit 123, as described later.

An operation unit (for example, a release button) 103 is provided on the camera body 101. When the operation unit 103 is pressed halfway, the control unit 124 causes the focus detection unit 123 to perform focus detection. Then, the control unit 124 drives and controls the lens driving unit 110 according to the focus detection result to focus the optical image (subject image) formed on the imaging unit 102.

When the operation unit 103 is fully pressed, the control unit 124 starts shooting. When capturing a still image, the control unit 124 drives a shutter (not shown) to obtain a still image from the image capturing unit 102. When capturing a moving image, the control unit 124 repeats image capturing by the image capturing unit 102 while keeping the shutter open. This makes it possible to obtain a moving image. It should be noted that when shooting a moving image, an autofocus mode in which a predetermined subject is always focused is used. The image data obtained by the image pickup unit 102 is subjected to predetermined processing by an image processing circuit (not shown), and then stored in a recording medium (not shown) such as a memory card. The operation unit 103 does not have to be a button, and may be a touch sensor or the like.

The lens driving unit 110 includes a first detection unit 115a and a second detection unit 114. Then, the detection results (described later) by the first detection unit 115a and the second detection unit 114 are sent to the control unit 124. The control unit 124 drives the driving unit 125 including a driver IC or the like according to the detection result to control the position of the lens driving unit 110.

FIG. 2 is a diagram for explaining the lens driving device shown in FIG. 2A is a front view, and FIG. 2B is a side view.

Referring also to FIG. 2, the lens barrel 105 includes a plurality of photographing lens groups (not shown) having the optical axis 111 as a central axis. The lens driving unit 110 has a lens (focus lens) 112 for performing focus adjustment. When the lens 112 moves along the optical axis 111 with respect to the lens barrel 105 that is the fixed portion, the focus state (that is, the focus) in the imaging unit 102 changes.

The lens 112 is held by a lens holding frame (holding member) 113, and the lens holding frame 113 is supported by a guide portion 117 fixed to the lens barrel 105 so as to be movable along the optical axis 111. When the coil 116a arranged in the lens holding frame 113 is energized, a thrust force is generated along the optical axis 111 by the electromagnetic action of the coil 116a and the magnet 116b fixed to the lens barrel 105 via the yoke 116c. Then, the thrust causes the lens 112 to move back and forth along the optical axis 111.

Here, the coil 116a, the magnet 116b, and the yoke 116c are collectively used as the drive source 116. In the illustrated example, a voice coil motor (VCM) using a coil and a magnet is used as the driving source 116, but a stepping motor and a lead screw may be combined to form the driving source. In addition, the drive source is not limited to the VCM as long as the drive source generates a force for driving the lens 112 along the optical axis 111.

The lens holding frame 113 is provided with a first detection unit 115 a for detecting the position of the lens holding frame 113 in the optical axis 111 direction. A scale 115b that repeats a bright and dark pattern is fixed to the lens barrel 105. The first detection unit 115a optically reads the pattern of the scale 115b and detects the position of the lens holding frame 113. In the illustrated example, a sensor that performs optical detection is used as the first detection unit 115a, but magnetic detection or mechanical detection may be performed. That is, the first detection unit 115a only needs to be able to detect the position of the lens holding frame 113 in the optical axis 111 direction.

The second detection unit 114 is for detecting information regarding the deformation of the lens holding frame 113. The second detection unit 114 is installed on the lens holding frame 113 between the lens 112 and the first detection unit 115a. As a result, the second detector 114 can sensitively detect a change in the positions of the first detector 115a and the lens 112 in the optical axis direction due to the deformation of the lens holding frame 113.

In the illustrated example, a strain gauge is used as the second detector 114. Then, the second detection unit 114 detects information regarding the deformation of the lens holding frame 113 according to the strain on the surface of the lens holding frame 113. The second detection unit 114 only needs to be able to detect information regarding the deformation of the lens holding frame 113, and for example, uses an optical detection method such as a piezoelectric element or a laser interferometer that converts the force applied to the piezoelectric body into a voltage. You can

FIG. 3 is a flowchart for explaining an example of AF (autofocus) performed by the camera shown in FIG.

First, the control unit 124 is instructed to start AF (autofocus) (step S301). Here, in the case of still image shooting, the control unit 124 starts AF when the button 103 is half pressed. In the case of moving image shooting, the control unit 124 starts AF by starting shooting. When the power is turned on and the image is displayed on the display unit (not shown), the control unit 124 may recognize the subject and start AF.

Subsequently, the control unit 124 determines the position of the lens 112 in the focused state as the target position according to the focus detection result output from the focus detection unit 123 (step S302). Then, the control unit 124 moves the lens 112 along the optical axis according to the current position and the target position of the lens 112 obtained by the first detection unit 115a (step S303). Although the movement of the lens 112 will be described later, the control unit 124 controls the drive source 116 using not only the detection result of the first detection unit 115a but also the detection result of the second detection unit 114.

Next, the control unit 124 compares the target position and the current position and determines whether the target position and the current position match (step S304). If they do not match (NO in step S304), the control unit 124 returns to the process of step S303. On the other hand, if they match (YES in step S304), the control unit 124 determines whether or not to finish the AF (step S305).

When it is determined that the AF is finished (YES in step S305), the control unit 124 finishes the AF process. On the other hand, when it is determined that the AF is not completed (NO in step S305), the control unit 124 returns to the process of step S302 to obtain the target position of the lens 112. It should be noted that the control unit 124 determines that the AF has ended when, for example, the pressing of the button 103 is stopped and the button 103 is released. Further, when the button 103 is fully pressed, the control unit 124 determines that the AF has ended. Further, when shooting a moving image, the control unit 124 temporarily stops AF according to a user instruction.

FIG. 4 is a diagram showing an example of functional blocks when performing AF processing in the control unit shown in FIG.

Upon receiving the focus detection result which is the output of the focus detection unit 123, the target position calculation unit 1241 obtains the target position (focus position) of the lens 112 according to the focus detection result. The subtractor 1242 subtracts the current position, which is the detection result of the first detection unit 115a, from the target position and outputs the position difference. The gain adjusting unit 1243 multiplies the position difference by a predetermined control gain to generate a drive signal indicating the control amount. On the other hand, the amount of deformation indicated by the detection result of the second detector 114 is given to the gain calculator 1243. Then, the gain adjusting unit 1243 adjusts the control gain according to the deformation amount when generating the drive signal as described later.

As described above, the control unit 124 corrects the drive amount obtained based on the difference according to the deformation amount to obtain the corrected drive amount, and controls the movement of the lens holding frame according to the corrected drive amount.

FIG. 5 is a diagram for explaining the deformation detected by the second detection unit shown in FIG.

In FIG. 5, the configuration of the lens driving unit 110 is partially omitted. When the lens holding frame 113 is driven along the optical axis 111 by the driving unit 116, the lens holding frame 113 may be deformed by the inertial force caused by the mass of the lens 112. Further, the natural vibration of the lens holding frame 113 may cause the lens holding frame 113 to vibrate.

For example, when the lens holding frame 113 is deformed as shown by the arrow D, the center position of the lens 112 shifts in the direction of the optical axis 111 by the shift amount E. That is, the current position of the lens 112 detected by the first detection unit 115a and the position of the center of the lens 112 in the optical axis 111 direction may differ by the amount of deviation E. This displacement amount E is primarily generated because it is caused by deformation and vibration due to the force in the moving direction, and approaches zero after a sufficient time has elapsed. However, when vibration occurs, it takes time until the vibration converges, and the responsiveness of lens movement is impaired.

Therefore, in the first embodiment, as described above, the second detection unit 114 is installed between the first detection unit 115a and the lens 112. The installation position of the second detection unit 114 is located at the root of deformation, and the deformation state of the lens 112 can be detected by measuring the strain on the surface of the lens holding frame 113. In general, the larger the deformation, the larger the deviation amount E. Therefore, if the deformation is controlled to be small, the deviation amount E can be reduced.

Referring again to FIG. 4, the gain calculation unit 1243 multiplies the position difference by the predetermined control gain as described above. However, the larger the control gain, the larger the driving unit 125 generates. Then, when a large force is generated in the driving unit 125, a large force is applied to the lens holding frame 113, and as a result, the deformation of the lens holding frame 113 becomes larger.

Therefore, the gain adjustment unit 1243 changes (adjusts) the control gain according to the detection result of the second detection unit 114. For example, the gain adjusting unit 1243 decreases the control gain as the deformation amount indicated by the information detected by the second detecting unit 114 increases. As a result, when the amount of deformation increases, the force generated by the drive unit 125 is suppressed, and the vibration generated in the lens holding frame 113 can be reduced.

Here, the control of the lens in the camera shown in FIG. 1 will be described in comparison with the conventional control.

FIG. 6 is a diagram for explaining changes in the target position, the lens holding frame position, and the lens center position over time in conventional lens movement control. And FIG.6(a) is a figure which shows the change of a target position, and FIG.6(b) is a figure which shows the change of a lens holding frame position. Further, FIG. 6C is a diagram showing a change in the lens center position. Here, the position means a position in the optical axis 111 direction.

In FIG. 6, the lens 112 starts moving at the timing when the target position changes. When the detection result of the first detection unit 115a indicating the position of the lens holding frame 113 reaches the target position, the movement of the lens holding frame 113 is stopped as shown in FIG. 6B. At this time, the larger the difference between the target position and the position of the lens holding frame 113, the higher the control gain. Therefore, as the lens holding frame 113 approaches the target position, the speed at which the lens holding frame 113 approaches the target position gradually decreases.

On the other hand, as shown in FIG. 6C, it can be seen that the center of the lens 112 is vibrated by the force generated by the driving unit 125 when the lens is moved. Then, the vibration continues even after the lens holding frame 113 shown in FIG. 6B is stopped. When the center position of the lens 112 is sufficiently close to the target position and falls within the range indicated by the broken line in FIG. 6C, it is determined that the target position has been reached. In other words, it is determined that the center position of the lens 112 continues to vibrate even after the movement of the lens holding frame 113 stops, and finally reaches the target position after the time t0.

FIG. 7 is a diagram for explaining changes in the target position, the lens holding frame position, and the lens center position over time due to the lens movement control in the camera shown in FIG. And FIG.7(a) is a figure which shows the change of a target position, and FIG.7(b) is a figure which shows the change of a lens holding frame position. Further, FIG. 7C is a diagram showing changes in the lens center position.

In FIG. 7, the lens 112 starts moving at the timing when the target position changes. Then, when the detection result of the first detection unit 115a indicating the position of the lens holding frame 113 reaches the target position, the movement of the lens holding frame 113 is stopped as shown in FIG. 7B. Here, as described above, the larger the deformation amount indicated by the detection result of the second detection unit 114, the smaller the control gain. That is, as the center position of the lens 112 changes largely with respect to the position of the lens holding frame 113, the control gain decreases. As a result, as shown in FIG. 7C, the vibration after the lens holding frame 111 is stopped is reduced, and it is determined that the target position is reached after the time t1 has elapsed.

Referring to FIGS. 6C and 7C, since time t1<time t0, the lens movement control performed by the camera shown in FIG. 1 requires lens movement, as compared with the conventional lens movement control. The time can be shortened. Thus, if the time required for AF can be shortened, the speed can be increased even when performing continuous AF. As a result, the responsiveness of lens movement control can be improved.

For example, in order to make the lens holding frame 113 highly rigid so that deformation does not occur, it is necessary to increase the volume by using a material having a high density. As a result, the mass of the frame 113 increases for the lens, and the responsiveness deteriorates. That is, in order to improve the responsiveness, it is important not to increase the mass of the lens holding frame 113 as much as possible. For this reason, it is desirable to use low density materials to reduce their volume. If a material having a low density is used, the lens holding frame 113 may be deformed. However, if the deformation of the lens holding frame 113 is canceled as described above, the lens 112 can be accurately positioned in a short time. Can be positioned at.

FIG. 8 is a diagram for explaining changes in the position of the lens holding frame used in the camera shown in FIG.

In FIG. 8, a broken line shows a change in the position of the lens holding frame 113 in the conventional lens movement control. The solid line indicates the change in the position of the lens holding frame 113 in the lens movement control performed by the camera shown in FIG. As shown in the figure, it can be seen that the movement speed of the lens holding frame 113 is faster in the conventional lens movement control until the target position is reached. That is, it can be seen that the lens holding frame 113 approaches the target position more quickly in the conventional lens movement control.

Since the lens holding frame 113 is deformed when the lens starts moving, in the camera shown in FIG. 1, the control gain is lowered according to the detection result of the second detection unit 114. As a result, in the camera shown in FIG. 1, the moving speed until reaching the target position decreases. On the other hand, in the camera shown in FIG. 1, by reducing the vibration as described above, the time required for the lens holding frame 113 to stop at the target position is shortened.

When it is desired to increase the moving speed of the lens 112, adjustment of the control gain according to the detection result of the second detection unit 114 is temporarily stopped when the movement of the lens 112 is started. Then, the control may be performed only based on the detection result of the first detection unit 115a. An example of a case where the moving speed of the lens 112 is desired to be high is a case where the shutter speed is sufficiently high. In this case, even if the vibration of the lens holding frame 113 is not subdued, there is no problem because shooting is performed in an instant when it is determined that the center position of the lens 112 has reached the target position.

As described above, since the deformation of the lens holding frame 113 is detected by the second detection unit 114, it is determined whether or not the center position of the lens 112 is at the instant when the center position reaches the target position even in the vibrating state. can do. As a result, the time required for AF can be shortened and the responsiveness can be improved.

[Second Embodiment]
Next, an example of a camera including the lens driving device according to the second embodiment of the present invention will be described. The configuration of the camera according to the second embodiment is similar to that of the camera shown in FIG. 1, and the configuration of the lens driving device according to the second embodiment is similar to that of the lens driving device shown in FIG.

FIG. 9 is a diagram showing an example of functional blocks when performing AF processing in the control unit included in the camera according to the second embodiment of the present invention. Note that, in FIG. 9, the function of the control unit is different from that of the control unit shown in FIG. Further, in FIG. 9, the first detection unit and the second detection unit are shown as the position detection unit 222 and the deformation detection unit 223, respectively. Further, in FIG. 9, the same components as those of the control unit shown in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted.

The displacement calculator 2244 multiplies the amount of deformation indicated by the output of the deformation detector 223 by a predetermined coefficient and outputs the displacement of the lens 212 in the optical axis direction. The displacement in the optical axis direction is equivalent to the shift amount E described in FIG. The adder 2245 adds the displacement output from the displacement calculator 2244 to the current position output from the position detector 222 to obtain the lens position.

In this way, the control unit 224 corrects the current position of the lens holding frame by the displacement of the lens holding frame to obtain the corrected current position (lens position).

The subtractor 2242 subtracts the lens position which is the output of the adder 2245 from the target position and outputs the position difference. Then, the position difference is sent to the gain adjusting unit 2243. The gain adjusting unit 2243 multiplies the position difference by a predetermined control gain and outputs a drive signal indicating the drive amount to the drive unit 125.

As described above, in the second embodiment, the displacement of the lens 212 in the optical axis direction is added to the current position of the lens holding frame 113 to obtain the position of the center of the lens 212 in the optical axis 211 direction (lens position). .. Then, the lens position is subtracted from the target position to control the center of the lens 212 to match the target position. Accordingly, when the lens 212 itself vibrates, it is possible to control so as to reduce the vibration.

FIG. 10 is a diagram for explaining changes in the target position, the lens holding frame position, and the lens center position over time due to the lens movement control described in FIG. And FIG.10(a) is a figure which shows the change of a target position, and FIG.10(b) is a figure which shows the change of a lens holding frame position. Further, FIG. 10C is a diagram showing a change in the lens center position.

In FIG. 10, the lens 112 starts moving at the timing when the target position changes. Then, when the detection result of the position detection unit 222 indicating the position of the lens holding frame 113 reaches the target position, the movement of the lens holding frame 113 is stopped as shown in FIG. 10B.

In the lens movement control according to the second embodiment, as described above, the control for aligning the center of the lens 212 with the target position is performed. As a result, as shown in FIG. 10C, the vibration after the lens 112 is stopped is reduced. Here, the center of the lens 112 reaches the target position when time t2 elapses after the target position changes.

Referring to FIGS. 6 and 10, time t2<time t0, and the lens movement control according to the second embodiment can shorten the time required for lens movement, as compared with the conventional lens movement control. Also in the second embodiment, continuous AF can be speeded up. As a result, the responsiveness of lens movement control can be improved.

[Third Embodiment]
Next, an example of a camera including the lens driving device according to the third embodiment of the present invention will be described. The configuration of the camera according to the third embodiment is similar to that of the camera shown in FIG. 1, and the configuration of the lens driving device according to the second embodiment is similar to that of the lens driving device shown in FIG.

FIG. 11 is a diagram showing an example of functional blocks when performing AF processing in a control unit included in a camera according to the third embodiment of the present invention. Note that, in FIG. 11, the function of the control unit is different from that of the control unit shown in FIG. Further, in FIG. 11, the first detection unit and the second detection unit are shown as the position detection unit 222 and the deformation detection unit 223, respectively. Further, in FIG. 9, the same components as those of the control unit shown in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted.

As described with reference to FIG. 4, the subtractor 1242 subtracts the current position from the target position and outputs the position difference. Then, the gain adjusting unit 3243 multiplies the position difference by a predetermined control gain and outputs a control signal indicating the control amount. On the other hand, the amount of deformation indicated by the output of the deformation detector 223 is input to the speed calculator 3246. The speed calculation unit 3246 obtains the deformation speed based on the time history of the deformation amount (that is, the temporal change amount). Then, the speed calculation unit 3246 sends the deformation speed obtained by multiplying the deformation speed by a predetermined coefficient to the adder 3247. The adder 3247 adds the deformation speed to the control signal output from the gain adjusting unit 3243 and sends it to the driving unit 125 as a driving signal.

In the third embodiment, the drive unit 125 is driven in consideration of the deformation speed obtained by multiplying the deformation speed obtained according to the temporal change of the deformation amount by a predetermined coefficient. As a result, the higher the deformation speed, the larger the driving amount of the driving unit 125, and the high-frequency vibration can be efficiently removed.

In the illustrated example, the deformation speed is added to the output of the gain adjustment unit 3243, but the gain adjustment unit 3243 may perform the control gain adjustment according to the deformation speed. That is, in the above-described first embodiment, the control gain is changed according to the deformation amount, but in the third embodiment, the control gain may be changed according to the deformation speed.

FIG. 12 is a diagram for explaining changes in the target position, the lens holding frame position, and the lens center position over time due to the lens movement control described in FIG. Then, FIG. 12A is a diagram showing a change in the target position, and FIG. 12B is a diagram showing a change in the lens holding frame position. Further, FIG. 12C is a diagram showing a change in the lens center position.

In FIG. 12, the lens 112 starts moving at the timing when the target position changes. Then, when the detection result of the position detection unit 222 indicating the position of the lens holding frame 113 reaches the target position, the movement of the lens holding frame 113 is stopped as shown in FIG. 12B.

In the lens movement control according to the third embodiment, as described above, the control for adjusting the center of the lens 212 to the target position is performed in consideration of the deformation speed obtained according to the temporal change of the deformation amount. As a result, as shown in FIG. 12C, the vibration after the lens 112 is stopped is greatly reduced. Here, the center of the lens 112 reaches the target position when time t3 elapses after the target position changes.

Referring to FIGS. 6 and 12, time t3<time t0, and the lens movement control according to the third embodiment can shorten the time required for lens movement, as compared with the conventional lens movement control. Also in the third embodiment, continuous AF can be sped up. As a result, the responsiveness of lens movement control can be improved.

[Fourth Embodiment]
Next, an example of a camera including the lens driving device according to the fourth embodiment of the present invention will be described. The configuration of the camera according to the fourth embodiment is similar to that of the camera shown in FIG.

FIG. 13 is a diagram for explaining an example of the lens driving device according to the fourth embodiment of the present invention. And FIG.13(a) is a front view and FIG.13(b) is a side view. Note that, in FIG. 13, the same components as those of the lens driving device shown in FIG.

The lens driving device shown in FIG. 13 differs from the lens driving device shown in FIG. 2 in the second detection unit. Therefore, in FIG. 13, the second detectors are indicated by reference numerals 414a to 414d. As illustrated, the second detectors 414a to 414d are arranged at both ends of the lens holding frame 113. That is, the second detectors 414a and 414b are arranged at the left end of the lens holding frame, and the second detectors 414a and 414b are arranged at the right end of the lens holding frame.

Here, the length of the lens holding frame 113 in the optical axis direction (fitting length) is L. The lens holding frame 113 is fitted to the guide portion 117 in the direction of the optical axis 111 with a length L, whereby the inclination of the lens 112 with respect to the optical axis 111 is minimized. On the other hand, in order to guide the lens holding frame 113 smoothly by the guide portion 117, it is necessary to form a slight gap (fitting play) between the lens holding frame 113 and the guide portion 117.

When the gap is formed in this way, the contact state between the lens holding frame 113 and the guide portion 117 changes due to the gap. When the contact state changes, the lens 112 may tilt with respect to the optical axis 111. In addition, the guide portion 117 requires at least the length L plus the moving distance of the lens holding frame 113. If the length L is increased in order to reduce the inclination of the lens 112, the guide portion 117 inevitably becomes longer, and the lens driving device becomes larger in the optical axis 111 direction. Therefore, in order to reduce the size of the lens driving device, it is necessary to reduce the length L. However, when the length L is reduced, the inclination of the lens 112 becomes large, and the center of the lens 112 is in the optical axis 111 direction. It may be out of alignment.

As described above, the illustrated lens driving device has the four second detectors 414a to 414d. The second detectors 414a and 414b and the second detectors 414c and 414d are arranged on the line connecting the guide 117 and the center of the lens 112 so as to sandwich the guide 117, respectively. Then, the control unit 124 determines the contact state between the lens holding frame 113 and the guide unit 117 according to the detection result of the second detection units 414a to 414d.

FIG. 14 is a diagram for explaining the detection of the contact state between the lens holding frame and the guide portion in the lens driving device shown in FIG. Then, FIG. 14A is a diagram showing a state where the lens is not tilted, and FIG. 14B is a diagram showing a state where the lens is tilted. Note that, in FIG. 14, a cross section passing through the centers of the guide portion 117 and the lens 112 in the lens driving device is shown with a part thereof omitted.

FIG. 14A shows a state in which the lens 112 is not tilted due to a gap (fitting play). In the state shown in FIG. 14A, a force is generated by the contact between the lens holding frame 113 and the guide portion 117, and the lens holding frame 113 is slightly deformed. Then, the deformation of the lens holding frame 113 is detected by the second detectors 414a and 414c. On the other hand, since the second detectors 414b and 414d are apart from the contact portion between the lens holding frame 113 and the guide portion 117, the deformation of the lens holding frame 113 cannot be detected.

Therefore, when the detection results are obtained by the second detectors 414a and 414c, that is, when the deformation of the lens holding frame 113 is detected, the controller 124 determines that the lens 112 is not tilted. Similarly, even when the deformation of the lens holding frame 113 is detected by the second detectors 414b and 414d, the controller 124 determines that the lens 112 is not tilted. In this case, the lens 112 is not displaced in the direction of the optical axis 111, and the center of the lens 112 is at the correct position.

FIG. 14B shows a state in which the lens holding frame 113 is biasedly contacted with the guide portion 117 and the lens 112 is tilted. In the state shown in FIG. 14B, since the vicinity of the portion where the lens holding frame 413 is in contact with the guide portion 417 is deformed, the detection results are obtained by the second detection portions 414a and 414d. Here, the lens 112 is tilted, and the position of the center of the lens 112 is shifted from the position in the state where there is no tilt to cause a shift G. The deviation G can be known in advance by design values and actual measurements during assembly.

Although not shown, when the detection results are obtained by the second detectors 414b and 414c, the lens 112 is tilted in the direction opposite to the state shown in FIG. 14B. Then, in this case, a shift G occurs in the direction opposite to the direction shown in FIG.

When the contact is biased in the direction in which the second detectors 414a to 414d are not arranged, any of the second detectors 414a to 414d can be deformed, that is, the inclination can be detected. Can not. In this case, the lens 112 is tilted in the direction orthogonal to the line connecting the center of the lens 112 and the guide portion 117. In addition, the influence of the center of the lens 112 deviating in the optical axis direction with respect to the inclination in that direction is slight. Therefore, in the fourth embodiment, as described above, the second detectors 414a to 414d are arranged at four places. However, the number of the second detection units may be increased in order to further improve the detection accuracy.

In the fourth embodiment, the control unit has the functional blocks shown in FIG. Here, the second detection units 414a to 414d correspond to the deformation detection unit 223. The deformation detection unit 223, that is, the detection results obtained by the second detection units 414a to 414d are sent to the displacement calculation unit 2244. The displacement calculator 2244 determines the state of the fitting backlash according to the detection results of the second detectors 414a to 414d. Then, the displacement calculator 2244 outputs the displacement in the optical axis direction depending on the presence or absence of the deviation G. After that, the drive of the drive unit 125 is controlled as described in the second embodiment.

As described above, in the fourth embodiment of the present invention, the contact state (that is, the fitting backlash) between the guide portion 117 and the lens holding frame 113 is detected, the bias direction of the contact is determined, and The drive unit 125 is controlled according to the bias direction. As a result, it is possible to improve the responsiveness of the lens movement control with high accuracy by coping with the deviation of the contact that occurs during the movement of the lens.

As is clear from the above description, in the example shown in FIG. 1, at least the lens drive unit 110, the focus detection unit 123, the first detection unit 115a, the second detection unit 114, the control unit 124, and the drive unit 125 are provided. A lens driving device is configured.

Although the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments, and various embodiments within the scope not departing from the gist of the present invention are also included in the present invention. .

For example, the function of the above-described embodiment may be used as a control method, and the control method may be executed by the lens driving device. Alternatively, a program having the functions of the above-described embodiments may be used as a control program, and the control program may be executed by a computer included in the lens driving device. The control program is recorded in, for example, a computer-readable recording medium.

[Other Embodiments]
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium. Then, it can be realized by a process in which one or more processors in the computer of the system or apparatus read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

105 lens barrel 110 lens drive unit 111 optical axis 112 lens 113 lens holding frame 114 second detection unit 115a first detection unit 117 guide unit 124 control unit

Claims (13)

A lens driving device for driving a lens in an optical axis direction,
A holding member that holds the lens and is movable in the optical axis direction,
First detection means for detecting a position of the holding member in the optical axis direction as a current position,
Second detection means, which is arranged on the holding member and detects information regarding deformation of the holding member;
Control means for controlling the movement of the holding member based on the information on the current position and the deformation;
A lens driving device comprising: A determining means for determining a target position of the lens in the optical axis direction,
The lens driving device according to claim 1, wherein the control unit controls movement of the holding member based on the target position, the current position, and information regarding the deformation. The control means obtains a drive amount when driving the holding member based on the target position and the current position, and corrects the drive amount based on the information regarding the deformation to obtain a corrected drive amount, The lens driving device according to claim 2, wherein movement of the holding member is controlled according to the correction driving amount. The control means obtains a difference between the target position and the current position as the drive amount, and when the drive amount is multiplied by a control gain, the control gain is changed based on information regarding the deformation to correct the correction amount. The lens drive device according to claim 3, wherein the drive amount is set. The lens driving device according to claim 4, wherein the control unit decreases the control gain as the deformation amount of the holding member indicated by the information regarding the deformation increases. The control means obtains a displacement of the holding member in the optical axis direction according to the information regarding the deformation, and corrects the current position by the displacement, and based on the corrected current position and the target position, The lens driving device according to claim 2, wherein movement of the holding member is controlled. 7. The control means adds the displacement to the current position to obtain the corrected current position, and controls the movement of the holding member according to a difference between the target position and the corrected current position. The lens driving device according to item 1. The control means obtains a deformation speed of the holding member based on a temporal change of a change amount indicated by the information regarding the deformation, and obtains the deformation speed based on the target position and the current position based on the deformation speed. The lens driving device according to claim 2, wherein the driving amount of the holding member is corrected to obtain a corrected driving amount, and the movement of the holding member is controlled according to the corrected driving amount. The first detection means is disposed on the holding member, and detects the position of the holding member in the optical axis direction,
9. The lens driving device according to claim 1, wherein the second detecting unit is arranged between the lens and the first detecting unit in the holding member. .. The holding member is movable along a guide portion extending in the optical axis direction,
9. The lens driving device according to claim 1, wherein the second detection unit is installed on the holding member near the guide unit. A lens driving device according to any one of claims 1 to 10,
An image pickup apparatus, wherein focus adjustment is performed using the lens. A method for controlling a lens driving device having a holding member which holds a lens and is movable in the optical axis direction,
A first detection step of detecting a position of the holding member in the optical axis direction as a current position;
A second detection step of detecting information on the deformation of the holding member using a detection means arranged on the holding member;
A control step of controlling the movement of the holding member based on the information on the current position and the deformation;
A control method comprising: A control program used in a lens driving device having a holding member that holds a lens and is movable in the optical axis direction,
In the computer provided in the lens driving device,
A first detection step of detecting a position of the holding member in the optical axis direction as a current position;
A second detection step of detecting information on the deformation of the holding member using a detection means arranged on the holding member;
A control step of controlling the movement of the holding member based on the information on the current position and the deformation;
A control program for executing the following.

Images